U.S. patent application number 14/739131 was filed with the patent office on 2015-10-01 for communication system and method using space division multi-user multiple input multiple output (sd-mimo) communication method.
This patent application is currently assigned to SAMSUNG ELECTRONICS CO., LTD.. The applicant listed for this patent is SAMSUNG ELECTRONICS CO., LTD.. Invention is credited to Eung Sun Kim, Young Soo Kim, Ui Kun Kwon, Tae Rim Park.
Application Number | 20150280799 14/739131 |
Document ID | / |
Family ID | 44081994 |
Filed Date | 2015-10-01 |
United States Patent
Application |
20150280799 |
Kind Code |
A1 |
Kwon; Ui Kun ; et
al. |
October 1, 2015 |
COMMUNICATION SYSTEM AND METHOD USING SPACE DIVISION MULTI-USER
MULTIPLE INPUT MULTIPLE OUTPUT (SD-MIMO) COMMUNICATION METHOD
Abstract
Provided is a communication system using a space division
multi-user multiple input multiple output (SD-MIMO) communication
method. A transmission apparatus may transmit, to each of terminals
included within a coverage, common control information commonly
transmitted to the terminals and individual control information
individually transmitted to each of the terminals. The transmission
apparatus does not precode the common control information and
transmits the non-precoded common control information. The
transmission apparatus precodes the individual control information
and transmits the precoded individual control information.
Inventors: |
Kwon; Ui Kun; (Hwaseong-si,
KR) ; Park; Tae Rim; (Hwaseong-si, KR) ; Kim;
Young Soo; (Seoul, KR) ; Kim; Eung Sun;
(Suwon-si, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SAMSUNG ELECTRONICS CO., LTD. |
Suwon-si |
|
KR |
|
|
Assignee: |
SAMSUNG ELECTRONICS CO.,
LTD.
Suwon-si
KR
|
Family ID: |
44081994 |
Appl. No.: |
14/739131 |
Filed: |
June 15, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14560333 |
Dec 4, 2014 |
9071296 |
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14739131 |
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14282083 |
May 20, 2014 |
8929482 |
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14560333 |
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12956526 |
Nov 30, 2010 |
8767858 |
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14282083 |
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Current U.S.
Class: |
375/267 |
Current CPC
Class: |
H04L 25/03343 20130101;
H04L 27/08 20130101; H04L 5/0023 20130101; H04B 7/0413 20130101;
H04B 7/0697 20130101; H04B 7/06 20130101; H04L 27/368 20130101;
H04B 7/0452 20130101; H04L 2025/03426 20130101; H04B 7/0456
20130101; H04L 5/0053 20130101; H04L 5/0092 20130101; H04L 25/0226
20130101; H04L 25/0202 20130101; H04L 25/0204 20130101 |
International
Class: |
H04B 7/04 20060101
H04B007/04; H04L 25/02 20060101 H04L025/02 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 4, 2009 |
KR |
10-2009-0119859 |
Claims
1. A method of an access point in a wireless network, comprising:
generating a first channel estimation field and a second channel
estimation field to be transmitted to a terminal; generating a
control field comprising a common control field and an individual
control field, wherein the common control field is to be
transmitted to the terminal subsequent to the first channel
estimation field and prior to the second channel estimation field,
and the individual control field is to be transmitted to the
terminal subsequent to the second estimation field; generating a
data field to be transmitted to the terminal subsequent to the
individual control field; and transmitting a space time stream
(STS) comprising the first and second channel estimation fields,
the common control field, the individual control field, and the
data field, wherein the common control field comprises information
of whether precoding is applied to the second channel estimation
field, to the individual control field, and to the data field of
the STS.
2. The method of claim 1, further comprising: generating a power
amplifier training field to be transmitted to the terminal
subsequent to the common control field and prior to the second
channel estimation field, wherein the power amplifier training
field comprises information to calibrate an automatic gain control
(AGC) for the STS.
3. The method of claim 1, wherein the common control field
comprises information to be used to interpret the STS at terminals
in the network that receive the STS.
4. The method of claim 1, wherein the individual control field
comprises information applied to the terminal in the network, which
receives the STS.
5. The method of claim 1, wherein the control field comprises
information of a number of at least one space time stream (STS) to
be transmitted to the terminal.
6. The method of claim 1, wherein the control field comprises
information of a length of the data field.
7. The method of claim 1, wherein the control field comprises
information of a modulation and coding rate applied to the data
field.
8. The method of claim 1, wherein the control field comprise
information of an error correction code applied to the data
field.
9. The method of claim 1, wherein the control field comprises
information of a length of a guard interval applied to the data
field.
10. The method of claim 1, wherein the second channel estimation
field comprises one or more estimation signal groups to be used to
estimate a channel between the access point and the terminal, and a
number of the estimation signal groups is dependent on a total
number of STSs transmitted from the access point to the terminal in
the network.
11. The method of claim 1, wherein the second channel estimation
field comprises one or more estimation signal groups to be used to
estimate a channel between the access point and the terminal, and
the signal groups have a same duration.
12. An access point in a wireless network transmitting a data field
to a terminal, comprising: a first channel estimator configured to
generate a first channel estimation field to be transmitted to the
terminal; a second channel estimator configured to generate a
second channel estimation field to be transmitted to the terminal;
a control information generator configured to generate a common
control field and an individual control field, and generate control
information corresponding to the common control field or the
individual control field; and transmitter configured to transmit a
space time stream (STS) comprising the first and second channel
estimation fields, the common control field, the individual control
field, and the data field, transmit the common control field
subsequent to the first channel estimation field and prior to the
second channel estimation field, and transmit the individual
control field subsequent to the second estimation field; wherein
the common control field comprises information of whether precoding
is applied to the second channel estimation field, to the
individual control field, and to the data field of the STS.
13. The access point of claim 12, further comprising: a training
signal generator configured to generate a power amplifier training
field to be transmitted to the terminal subsequent to the common
control field and prior to the second channel estimation field,
wherein the power amplifier training field comprises information to
calibrate an automatic gain control (AGC) for the STS.
14. The access point of claim 12, wherein the control information
comprises information to be used to interpret the STS at terminals
in the network that receive the STS.
15. The access point of claim 12, wherein the individual control
field comprises information applied to the terminal in the network,
which receives the STS.
16. The access point of claim 12, wherein the control information
comprises information of a number of at least one space time stream
(STS) to be transmitted to the terminal.
17. The access point of claim 12, wherein the control information
comprises information of a length of the data field.
18. The access point of claim 12, wherein the control information
comprises information of a modulation and coding rate applied to
the data field.
19. The access point of claim 12, wherein the control information
comprise information of an error correction code applied to the
data field.
20. The access point of claim 12, wherein the control information
comprises information of a length of a guard interval applied to
the data field.
21. The access point of claim 12, wherein the second channel
estimation field comprises one or more estimation signal groups to
be used to estimate a channel between the access point and the
terminal, and a number of the estimation signal groups is dependent
on a total number of STSs transmitted from the access point to the
terminal in the network.
22. The access point of claim 12, wherein the second channel
estimation field comprises one or more estimation signal groups to
be used to estimate a channel between the access point and the
terminal, and the signal groups have a same duration.
23. A method of a terminal in a wireless network, comprising:
receiving a first channel estimation field and a second channel
estimation field from an access point; receiving, from the access
point, a control field comprising a common control field and an
individual control field, wherein the common control field is
received subsequent to the first channel estimation field and prior
to the second channel estimation field, and the individual control
field is received subsequent to the second estimation field;
receiving, from the access point, a data field from the access
point subsequent to the individual control field, wherein a space
time stream (STS) comprises the first and second channel estimation
fields, the common control field, the individual control field, and
the data field; and decoding the STS based on the common control
field, wherein the common control field comprises information of
whether precoding has been applied to the second channel estimation
field, to the individual control field, and to the data field of
the STS.
24. The method of claim 23, further comprising: receiving, from the
access point, a power amplifier training field subsequent to the
common control field and prior to the second channel estimation
field, wherein the power amplifier training field comprises
information to calibrate an automatic gain control (AGC) in a
multi-input multi-output transmission of the STS.
25. The method of claim 23, wherein the common control field
comprises information which is applied to the STS regardless of a
terminal intended for the STS.
26. The method of claim 23, wherein the individual control field
comprises information that is specific to the terminal.
27. The method of claim 23, wherein the control field comprises
information of a number of at least one space time stream (STS) to
be transmitted to the terminal.
28. The method of claim 23, wherein the control field comprises
information of a length of the data field.
29. The method of claim 23, wherein the control field comprises
information of a modulation and coding rate applied to the data
field.
30. The method of claim 23, wherein the control field comprises
information of an error correction code applied to the data
field.
31. The method of claim 23, wherein the control field comprises
information of a length of a guard interval applied to the data
field.
32. The method of claim 23, wherein the second channel estimation
field comprises one or more estimation signal groups to be used to
estimate a channel between the access point and the terminal, and a
number of the estimation signal groups is dependent on a total
number of at least one STS transmitted from the access point to
terminals in the network.
33. The method of claim 23, wherein the second channel estimation
field comprises one or more estimation signal groups to be used to
estimate a channel between the access point and the terminal, and
the signal groups have a same duration.
34. A terminal in a wireless network, comprising: a receiver
configured to receive a first channel estimation field and a second
channel estimation field from an access point, receive from the
access point a control field comprising a common control field and
an individual control field, and receive from the access point a
data field subsequent to the individual control field, wherein the
common control field is received subsequent to the first channel
estimation field and prior to the second channel estimation field,
and the individual control field is received subsequent to the
second estimation field, and wherein a space time stream (STS)
comprises the first and second channel estimation fields, the
common control field, the individual control field, and the data
field; and a decoder configured to decode the STS based on the
common control field, wherein the common control field comprises
information of whether precoding has been applied to the second
channel estimation field, to the individual control field, and to
the data field of the STS.
35. The terminal of claim 34, wherein the receiver is further
configured to receive from the access point a power amplifier
training field subsequent to the common control field and prior to
the second channel estimation field, and wherein the power
amplifier training field comprises information to calibrate an
automatic gain control (AGC) in a multi-input multi-output
transmission of the STS.
36. The terminal of claim 34, wherein the common control field
comprises information which is applied to the STS regardless of a
terminal intended for the STS.
37. The terminal of claim 34, wherein the individual control field
comprises information that is specific to the terminal.
38. The terminal of claim 34, wherein the control field comprises
information of a number of at least one space time stream (STS) to
be transmitted to the terminal.
39. The terminal of claim 34, wherein the control field comprises
information of a length of the data field.
40. The terminal of claim 34, wherein the control field comprises
information of a modulation and coding rate applied to the data
field.
41. The terminal of claim 34, wherein the control field comprises
information of an error correction code applied to the data
field.
42. The terminal of claim 34, wherein the control field comprises
information of a length of a guard interval applied to the data
field.
43. The terminal of claim 34, wherein the second channel estimation
field comprises one or more estimation signal groups to be used to
estimate a channel between the access point and the terminal, and a
number of the estimation signal groups is dependent on a total
number of at least one STS transmitted from the access point to
terminals in the network.
44. The terminal of claim 34, wherein the second channel estimation
field comprises one or more estimation signal groups to be used to
estimate a channel between the access point and the terminal, and
the signal groups have a same duration.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This present application is a continuation of U.S. patent
application Ser. No. 14/560,333 filed Dec. 4, 2014, which is a
continuation of U.S. patent application Ser. No. 14/282,083 filed
May 20, 2014, which is a continuation of U.S. patent application
Ser. No. 12/956,526 filed Nov. 30, 2010, which claims the benefit
under 35 U.S.C. .sctn.119(a) of Korean Patent Application No.
10-2009-0119859, filed on Dec. 4, 2009, in the Korean Intellectual
Property Office, the entire disclosures of which are incorporated
herein by reference for all purposes.
BACKGROUND
[0002] 1. Field
[0003] The following description relates to a method of
transmitting and receiving data using a wireless network.
[0004] 2. Description of Related Art
[0005] In a space division multi-user multiple input multiple
output (SD-MIMO) communication method, precoding may correspond to
a process of appropriately allocating spatial beams to users.
[0006] Multiple-input and multiple-output (MIMO) includes three
main categories: precoding, spatial multiplexing or SM, and
diversity coding. Beamforming increases the signal gain from
constructive interference and reduces the multipath fading effect.
When the receiver has multiple antennas, precoding is used to
simultaneously maximize the signal level at the receiving antennas.
In spatial multiplexing, a high rate signal is split into multiple
lower rate streams, and each stream is transmitted from a different
transmit antenna in the same frequency channel. In diversity
coding, a single stream is coded using space-time coding and
transmitted. Spatial multiplexing can also be combined with
precoding or combined with diversity coding.
[0007] A transmission apparatus may receive channel status
information from terminals, and may select a terminal to receive
data using precoding based on the received channel status
information. The transmission apparatus may perform precoding based
on the channel status information.
[0008] A terminal may receive a training signal from the
transmission apparatus, and estimate a channel between the
transmission apparatus and the terminal using the received training
signal to generate channel status information.
[0009] In the SD-MIMO communication method, the transmission
apparatus may employ a plurality of transmit antennas and thus the
channel between the transmission apparatus and the terminal may be
provided in a vector or matrix form. To estimate the channel in the
vector or matrix form, the transmission apparatus may transmit an
individual training signal for each transmit antenna.
SUMMARY
[0010] A transmission apparatus to transmit data to a plurality of
terminals comprising at least one receive antenna, the transmission
apparatus comprising a common control information generator
configured to generate common control information with respect to
the plurality of terminals. an individual control information
generator configured to generate individual control information
with respect to each of the terminals. a precoder configured to
generate precoded data with respect to each of the terminals by
precoding the individual control information and data with respect
to each of the terminals and a transmitter configured to transmit,
to the plurality of terminals, a data frame comprising the common
control information and the precoded data according to a multi-user
multiple input multiple output (MU-MIMO) communication method.
[0011] The common control information comprises one or more of a
precoding method applied to the data frame, a number of terminals
supported by the data frame, a number of data streams included in
the data frame, a duration or a length of a channel estimation
field included in the data frame, and a format of the channel
estimation field.
[0012] A power amplifier training signal generator configured to
generate a power amplifier training signal for a multi-antenna
automatic gain control (AGC) of each of the terminals, wherein the
precoder is further configured to generate the precoded data by
additionally precoding the power amplifier training signal.
[0013] The individual control information comprises one or more of
a length of the data frame, a modulation and coding method applied
to the data with respect to each of the terminals, a channel
bandwidth, a channel smoothing, a channel aggregation, an error
correction code, and a length of a guard interval.
[0014] A channel estimation signal generator configured to generate
a channel estimation signal used for a channel estimation of each
of the terminals, wherein the precoder is further configured to
generate the precoded data by additionally precoding the channel
estimation signal.
[0015] In one general aspect, there is provided a transmission
apparatus to transmit data to a plurality of terminals including at
least one receive antenna, the transmission apparatus including: a
common control information generator configured to generate common
control information with respect to the plurality of terminals, an
individual control information generator configured to generate
individual control information with respect to each of the
terminals, a precoder configured to generate precoded data with
respect to each of the terminals by precoding the individual
control information and data with respect to each of the terminals,
and a transmitter configured to transmit, to the plurality of
terminals, a data frame including the common control information
and the precoded data according to a multi-user multiple input
multiple output (MU-MIMO) communication method.
[0016] The transmission apparatus may include that the common
control information includes one or more of: a precoding method
applied to the data frame, a number of terminals supported by the
data frame, a number of data streams included in the data frame, a
duration or a length of a channel estimation field included in the
data frame, and a format of the channel estimation field.
[0017] The transmission apparatus may further include including: a
power amplifier training signal generator configured to generate a
power amplifier training signal for a multi-antenna automatic gain
control (AGC) of each of the terminals, wherein the precoder is
further configured to generate the precoded data by additionally
precoding the power amplifier training signal.
[0018] The transmission apparatus may include that the individual
control information includes one or more of: a length of the data
frame, a modulation and coding method applied to the data with
respect to each of the terminals, a bandwidth of a using channel, a
channel smoothing, a channel aggregation, an error correction code,
and a length of a guard interval.
[0019] The transmission apparatus may further include: a channel
estimation signal generator configured to generate a channel
estimation signal used for a channel estimation of each of the
terminals, wherein the precoder is further configured to generate
the precoded data by additionally precoding the channel estimation
signal.
[0020] The transmission apparatus may further include: a controller
configured to: individually determine a number of data streams
transmitted to each of the terminals, and determine a number of
channel estimation signal groups based on the number of data
streams, wherein the data frame includes a plurality of data
streams, and wherein the channel estimation signal includes a
plurality of channel estimation signal groups.
[0021] The transmission apparatus may include that: the transmitter
is further configured to transmit a plurality of precoded data to a
particular terminal included in the plurality of terminals, and
each of channel estimation signals included in the plurality of
precoded data is included in a different time interval.
[0022] The transmission apparatus may include that the individual
control information is modulated using a predetermined modulation
method, or is error correction coded using a predetermined error
correction code method.
[0023] In another general aspect, there is provided a terminal
connected to a transmission apparatus, the terminal including: a
receiver configured to receive a data frame from the transmission
apparatus, a common control information decoder configured to
decode, from the data frame, common control information commonly
transmitted to the terminal and to a second terminal that are
connected to the transmission apparatus, an individual control
information decoder configured to decode, from the data frame,
individual control information individually determined with respect
to each of the terminal and the second terminal based on the common
control information, and a data decoder configured to decode data,
included in the data frame, based on the individual control
information, wherein the individual control information and the
data are precoded and are received.
[0024] The terminal may include that the common control information
includes one or more of: a precoding method applied to the data
frame, a number of terminals supported by the data frame, a number
of data streams included in the data frame, a duration or a length
of a channel estimation field included in the data frame, and a
format of the channel estimation field.
[0025] The terminal may include that the individual control
information includes one or more of: a length of the data frame, a
modulation and coding method applied to the data with respect to
each of the terminals, a bandwidth of a using channel, a channel
smoothing, a channel aggregation, an error correction code, and a
length of a guard interval.
[0026] The terminal may include that the individual control
information decoder is further configured to decode the individual
control information using a predetermined modulation method or a
predetermined error correction code method.
[0027] The terminal may further include: a channel estimator
configured to estimate a channel between the terminal and the
transmission apparatus based on a channel estimation signal,
wherein the data frame includes the channel estimation signal, and
wherein the data decoder is further configured to decode the data
based on the estimated channel.
[0028] The terminal may include that: the data frame includes a
plurality of data streams, each of the data streams includes the
channel estimation signal, and the channel estimation signal
included in each of the data streams is included in a different
time interval.
[0029] The terminal may include that: the data frame includes a
plurality of data streams, the channel estimation signal includes a
plurality of channel estimation signal groups, and a number of the
channel estimation signal groups is determined based on a number of
the data streams.
[0030] The terminal may include that the receiver is further
configured to receive the data frame via at least one receive
antenna.
[0031] In another general aspect, there is provided a method of
transmitting data to a plurality of terminals including at least
one receive antenna, the method including: generating common
control information with respect to the plurality of terminals,
generating individual control information with respect to each of
the terminals, generating precoded data with respect to each of the
terminals by precoding the individual control information and data
with respect to each of the terminals, and transmitting, to the
plurality of terminals, a data frame including the common control
information and the precoded data according to a MU MIMO
communication method.
[0032] The method may include that the common control information
includes one or more of: a precoding method applied to the data
frame, a number of terminals supported by the data frame, a number
of data streams included in the data frame, a duration or a length
of a channel estimation field included in the data frame, and a
format of the channel estimation field.
[0033] The method may include that the individual control
information includes one or more of: a length of the data frame, a
modulation and coding method applied to the data with respect to
each of the terminals, a bandwidth of a using channel, a channel
smoothing, a channel aggregation, an error correction code, and a
length of a guard interval.
[0034] The method may further include: generating a channel
estimation signal used for a channel estimation of each of the
terminals, wherein the precoding includes generating the precoded
data by additionally precoding the channel estimation signal.
[0035] In another general aspect, there is provided a method of
receiving data, the method including: receiving a data frame from
the transmission apparatus, decoding, from the data frame, common
control information commonly transmitted to the terminal and to a
second terminal that are connected to the transmission apparatus,
decoding, from the data frame, individual control information
individually determined with respect to each of the terminal and
the second terminal based on the common control information, and
decoding data, included in the data frame, based on the individual
control information, wherein the individual control information and
the data are precoded and are received.
[0036] The method may further include: estimating a channel between
the terminal and the transmission apparatus based on a channel
estimation signal, wherein the data frame includes the channel
estimation signal, and the decoding of the data includes decoding
the data based on the estimated channel.
[0037] The method may include that: the data frame includes a
plurality of data streams, each of the data streams includes the
channel estimation signal, and the channel estimation signal
included in each of the data streams is included in a different
time interval.
[0038] In another general aspect, there is provided a
non-transitory computer-readable recording medium storing a program
to implement the method of claim 17.
[0039] Other features and aspects will be apparent from the
following detailed description, the drawings, and the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0040] FIG. 1 is a diagram illustrating a data transmission using a
multi-user multiple input multiple output (MU-MIMO) communication
method according to an embodiment.
[0041] FIG. 2 is a diagram illustrating a structure of a data frame
according to an embodiment.
[0042] FIG. 3 is a diagram illustrating a structure of a data frame
further including legacy control information to support terminals
according to an embodiment.
[0043] FIG. 4 is a diagram illustrating a data frame when a
particular terminal receives a plurality of data streams according
to an embodiment.
[0044] FIG. 5 is a diagram illustrating an example of a data frame
in which data streams are independently separated and transmitted
using precoding
[0045] FIG. 6 is a diagram illustrating an example of data streams
including channel estimation signal groups in different time
intervals with respect to the same terminal according to an
embodiment.
[0046] FIG. 7 is a diagram illustrating an example of data streams
including channel estimation signal groups in different time
intervals with respect to different terminals according to an
embodiment.
[0047] FIG. 8 is a diagram illustrating an example of a data frame
in which data streams are independently separated and transmitted
using precoding.
[0048] FIG. 9 is a block diagram illustrating a configuration of a
transmission apparatus according to an embodiment.
[0049] FIG. 10 is a block diagram illustrating a configuration of a
terminal according to an embodiment.
[0050] FIG. 11 is a flowchart illustrating a method of receiving
data according to an embodiment.
[0051] FIG. 12 is a flowchart illustrating a method of transmitting
data according to an embodiment.
[0052] Throughout the drawings and the detailed description, unless
otherwise described, the same drawing reference numerals will be
understood to refer to the same elements, features, and structures.
The relative size and depiction of these elements may be
exaggerated for clarity, illustration, and convenience.
DETAILED DESCRIPTION
[0053] The following detailed description is provided to assist the
reader in gaining a comprehensive understanding of the methods,
apparatuses, and/or systems described herein. Accordingly, various
changes, modifications, and equivalents of the systems,
apparatuses, and/or methods described herein will be suggested to
those of ordinary skill in the art. The progression of processing
steps and/or operations described is an example; however, the
sequence of and/or operations is not limited to that set forth
herein and may be changed as is known in the art, with the
exception of steps and/or operations necessarily occurring in a
certain order. Also, description of well-known functions and
constructions may be omitted for increased clarity and
conciseness.
[0054] FIG. 1 illustrates a data transmission using a multi-user
multiple input multiple output (MU-MIMO) communication method
according to an embodiment.
[0055] Referring to FIG. 1, a transmission apparatus 110 transmits
data to terminals 181 and 182 via transmit antennas 151 and 152. A
precoder 140 of the transmission apparatus 110 may precode data
streams 120 and 130 using a precoding matrix.
[0056] The precoded data streams may be transmitted to the
terminals 181 and 182 using vector channels 161, 162, 163, and 164.
Although the illustrated terminal 181 includes a single receive
antenna 171 and the terminal 182 includes a single receive antenna
172 in FIG. 1, each of the terminals 181 and 182 may include a
plurality of receive antennas.
[0057] Each of the terminals 181 and 182 may receive the data
streams transmitted using the vector channels 161, 162, 163, and
164. A signal received by the terminal 181 may be expressed by the
following Equation 1.
[ y 1 ] = [ h 11 h 12 ] [ t 11 t 21 ] [ x 1 ] + [ h 11 h 12 ] [ t
12 t 22 ] [ x 2 ] + [ n 1 ] [ Equation 1 ] ##EQU00001##
[0058] A signal received by the terminal 182 may be expressed by
the following Equation 2.
[ y 2 ] = [ h 21 h 22 ] [ t 11 t 21 ] [ x 1 ] + [ h 21 h 22 ] [ t
12 t 22 ] [ x 2 ] + [ n 2 ] [ Equation 2 ] ##EQU00002##
[0059] In one example, x1 and x2 denote the data streams to be
transmitted from the transmission apparatus 110 to the terminals
181 and 182, respectively; y1 and y2 denote the signals received by
the terminals 181 and 182, respectively; and h11, h12, h21, and h22
denote statuses of radio channels formed between each of the
transmit antennas 151 and 152 and each of the receive antennas 171
and 172. Also, [t11, t21] denotes a precoding vector of the
terminal 181, [t12, t22] denotes a precoding vector of the terminal
182, and n1 and n2 denote thermal noise.
[0060] Referring to the above Equation 1, the transmission
apparatus 110 may determine the precoding vector [t12, t22] such
that an inner product value of a channel vector [h11 h12] with
respect to the terminal 181 and the precoding vector [t12, t22]
with respect to the terminal 182 may become a very small value. In
one example, interference of the data stream x2 against the
terminal 181 may decrease.
[0061] Similarly, referring to the above Equation 2, the
transmission apparatus may determine the precoding vector [t11,
t21] such that an inner product value of a channel vector [h21 h22]
with respect to the terminal 182 and the precoding vector [t11,
t21] with respect to the terminal 181 may become a very small
value. In one example, interference of the data stream x1 against
the terminal 182 may decrease.
[0062] The transmission apparatus 110 may receive channel status
information from each of the terminals 181 and 182 to verify the
channel status information, and may determine a precoding vector so
that a channel vector and the precoding vector may mutually have a
small inner product value.
[0063] When the transmission apparatus 110 transmits, to the
terminals 181 and 182, a data frame including a first data frame
and a second data frame, a length of the second data frame received
by the terminal 181 may be very short. Accordingly, an amount of
interference caused by the second data stream may be very small and
the terminal 181 may decode the first data stream. Similarly, the
terminal 182 may decode the second data stream.
[0064] Each of the terminals 181 and 182 may receive a training
signal from the transmission apparatus 110 to estimate a channel
status using the training signal. As shown in FIG. 1, when the
transmission apparatus 110 includes the plurality of transmit
antennas 151 and 152, the transmission apparatus 110 may transmit a
specially designed training signal to each of the terminals 181 and
182, such that each of the terminals 181 and 182 may identify the
training signal transmitted from each of the transmit antennas 151
and 152.
[0065] FIG. 2 illustrates a structure of a data frame according to
an embodiment. The data frame includes a signal detection field
211, a first channel estimation field 212, a common control field
213, and precoded data 220.
[0066] Precoding may not be applied to the signal detection field
211, the first channel estimation field 212, and the common control
field 213.
[0067] The precoded data 220 corresponds to information that is
precoded and may be transmitted to each terminal, e.g., the
terminals 181 and 182 in FIG. 1. Accordingly, the precoded data 220
may include control information or data that is individually
determined for each terminal. The precoded data 220 may include a
power amplifier training field 230, a second channel estimation
field 240, an individual control field 250, and a data field
260.
[0068] A terminal, e.g., the terminals 181 and 182, may detect a
received frame using the signal detection field 211, and may set a
gain value of a power amplifier. The terminal may also estimate a
coarse time synchronization with respect to the received frame, and
estimate a frequency offset.
[0069] The terminal may estimate a fine frequency offset using the
first channel estimation field 212. The terminal may estimate a
channel for decoding of a channel estimation field.
[0070] The terminal may detect common control information with
respect to a data frame currently being transmitted using the
common control field 213. The common control information may
include one or more of: a precoding method applied to the data
frame, a number of terminals supported by the data frame, a number
of data frames included in the data frame, a duration or a length
of the second channel estimation field 240, and a format of the
second channel estimation field 240.
[0071] The power amplifier training field 230 may include a
training signal to enhance a multi-antenna automatic gain control
(AGC) performance. The terminal may set a fine gain value of a
power amplifier appropriate for a precoded signal using the power
amplifier training field 230.
[0072] The terminal may accurately estimate a channel for decoding
of the precoded individual control field 250 and the data field 260
using the second channel estimation field 240.
[0073] The terminal may receive the individual control field 250 to
detect individual control information of a data frame transmitted
to each terminal. Control information corresponding to each
terminal may be precoded and simultaneously be transmitted.
[0074] Individual control information may include one or more of: a
length of the data field 260 or the data frame transmitted to a
corresponding terminal, a modulation and coding method applied to
the data field 260, a channel bandwidth, a channel smoothing, a
channel aggregation, an error correction code, a length of a guard
interval.
[0075] As described above, the information in the common control
field 213 is not precoded while the information in the individual
control field 250 is precoded. In other words, the information in
the common control field 213 may be decoded by each terminal in the
system, but the information included in the individual control
field 250 may be decoded only by an intended terminal. As such, the
type of information to be not precoded (and therefore to be decoded
by each terminal) may be included in the common control field 213,
and the type of information to be precoded (and therefore to be
decoded only by an intended terminal) may be included in the
individual control field 250. For example, a number of data frames
included in the data frame, a duration or a length of the second
channel estimation field 240 and a format of the second channel
estimation field 240 described above as the information included in
the common control field 213 may instead be included in the
individual control field 250. Also, a length of the data field 260
or the data frame transmitted to a corresponding terminal, a
modulation and coding method applied to the data field 260, a
channel bandwidth, a channel smoothing, a channel aggregation, an
error correction code and a length of a guard interval described
above as the information included in the individual control field
250 may instead be included in the common control field 213.
[0076] FIG. 3 illustrates a structure of a data frame further
including legacy control information to support terminals according
to an embodiment.
[0077] Referring to FIG. 3, the data frame includes a signal
detection field 311, a first channel estimation field 312, a legacy
control field 320, a common control field 313, and precoded data
370.
[0078] Precoding is not applied to the signal detection field 311,
the channel estimation field 312, and the common control field 313.
In other words, it is not necessary to precode the signal detection
field 311, the channel estimation field 312, and the common control
field 313. Accordingly, as similar to the description made above
with reference to FIG. 2, a terminal, e.g., terminals 181 and 182
in FIG. 1, supporting a space division multi-user multiple input
multiple output (SD-MIMO) communication method may receive the
signal detection field 311, the first channel estimation field 312,
and the common control field 313 and use these fields to receive
the precoded data 370.
[0079] Precoding is not applied to the legacy control field 320. In
other words, it is not necessary to precode the legacy control
field 320. Accordingly, an existing terminal not supporting the
SD-MIMO communication method may also receive the legacy control
field 320 using the signal detection field 311, the first channel
estimation field 312, and the common control field 313. Using the
legacy control field 320, the existing terminal may detect
information associated with a modulation and coding method applied
to a data field 360 and a frame length.
[0080] The existing terminal may verify a time interval in which
the precoded data field 360 is transmitted and not receive the
precoded data field 360.
[0081] The terminal supporting the SD-MIMO communication method may
receive the precoded data field 360 using the common control field
313. The common control field 313 is similar to the common control
field 213 of FIG. 2.
[0082] The precoded data 370 may include a power amplifier training
field 330, a second channel estimation field 340, an individual
control field 350, and the data field 360. The power amplifier
training field 330, the individual control field 350, and the data
field 360 of FIG. 3 are similar to the power amplifier training
field 230, the individual control field 250, and the data field 260
of FIG. 2.
[0083] A terminal may estimate a channel between a transmission
apparatus and the terminal using the second channel estimation
field 340. The second channel estimation field 340 may include a
plurality of channel estimation signal groups 341 and 342. The
terminal may estimate the channel between the transmission
apparatus and the terminal by combining the plurality of channel
estimation signal groups 341 and 342.
[0084] When using the data frame of FIG. 3, an advanced terminal
supporting the SD MIMO communication method may receive the common
control field 313 and even an existing terminal not supporting the
SD-MIMO communication method may receive the legacy control field
320. The existing terminal may detect a length of the precoded data
field 360 transmitted to the advanced terminal using the legacy
control field 320 and then may terminate a reception.
[0085] FIG. 4 illustrates a data frame when a particular terminal
receives a plurality of data streams 491, 492, and 493 according to
an embodiment.
[0086] Referring to FIG. 4, the data frame supports two terminals,
for example, a first terminal and a second terminal, e.g.,
terminals 181 and 182 in FIG. 1. The data frame includes the
plurality of data streams 491, 492, and 493. Among the data streams
491, 492, and 493, the data streams 491 and 492 may be transmitted
to the first terminal, and the data stream 493 may be transmitted
to the second terminal.
[0087] A signal detection field 411, a first channel estimation
field 412, and a common control field 413 are not precoded and may
be transmitted to each of the first terminal and the second
terminal. The signal detection field 411, the first channel
estimation field 412, and the common control field 413 of FIG. 4
include similar information to the signal detection field 211, the
first channel estimation field 212, and the common control field
213 of FIG. 2.
[0088] Precoded data 420 is precoded with respect to the particular
terminal and may be decoded only by the particular terminal to
which it is directed. In one example, only the particular terminal
would have the capability of decoding the precoded data 420. The
precoded data 420 included in each of the data streams 491, 492,
and 493 may include a power amplifier training field 430, a second
channel estimation field 440, an individual control field 450, and
a data field 460.
[0089] The first terminal may decode precoded data 431, 441, 442,
451, and 461 included in the data stream 491. The first terminal
may also decode precoded data 432, 443, 444, and 462 included in
the data frame 492. The second terminal may decode precoded data
433, 445, 452, and 463 included in the data stream 493.
[0090] The power amplifier training field 430 is precoded and
transmitted to each of the first terminal and the second terminal.
The power amplifier training field 430 of FIG. 4 is similar to the
power amplifier training field 230 of FIG. 2.
[0091] The second channel estimation field 440 included in each of
the data streams 491, 492, and 493 may include at least one of
channel estimation signal groups 441, 442, 443, 444, and 445.
[0092] A number of channel estimation signal groups included in
each of the data streams 491, 492, and 493 may be determined based
on a number of data streams to be transmitted to each of the first
terminal and the second terminal. In other words, there may be one
channel estimation group for each respective data stream to be
transmitted.
[0093] For example, when two data streams 491 and 492 are
transmitted to the first terminal, the data stream 491 may include
at least two channel estimation signal groups, e.g., the channel
estimation signal groups 441 and 442; and the data stream 492 may
include at least two channel estimation signal groups, e.g., the
channel estimation group 443 and 444.
[0094] When only the single data stream 493 is transmitted to the
second terminal, the data stream 493 may include a single channel
estimation signal group, e.g., the channel estimation signal group
445.
[0095] The first terminal receiving the data streams 491 and 492
may estimate a channel between a plurality of transmit antennas and
the first terminal by combining the channel estimation signal
groups 441, 442, 443, and 444. In other words, all of the channel
estimation groups in each received stream, e.g., data streams 491
and 492 in the illustrated example, may be used to estimate the
channel.
[0096] The second terminal receiving the single data stream 493 may
estimate a channel between a transmit antenna and the second
terminal using only the channel estimation signal group 445. Again,
all of the channel estimation groups in each received stream, e.g.,
data stream 493 by itself, in the illustrated example, may be used
to estimate the channel.
[0097] Individual control information included in each of
individual control fields 451 and 452 includes information similar
to the individual control information included in the individual
control field 250 of FIG. 2.
[0098] Each of the first terminal and the second terminal may be
aware of a number of data streams transmitted to a corresponding
terminal based on the individual control information. The
individual control information may keep track of how many data
streams are transmitted. Each of the first terminal and the second
terminal may be aware of the number of channel estimation signal
groups included in each data stream based on the number of data
streams transmitted to each of the first terminal and the second
terminal. The individual control information may keep track of how
many channel estimation signal groups are included.
[0099] Each of the first terminal and the second terminal may
estimate a channel using a corresponding channel estimation signal
group. The first and second terminals may also decode data fields
461, 462, and 463 transmitted to each of the first terminal and the
second terminal.
[0100] In FIG. 4, two terminals, e.g., terminals 181 and 182, may
receive data frames. According to another embodiment, a single
terminal or at least three terminals may receive data frames. In
one example, a number of channel estimation signal groups included
in the second channel estimation field 440 may be determined based
on a number of data streams received by each terminal.
[0101] FIG. 5 illustrates an example of a data frame in which data
streams are independently separated and transmitted using
precoding.
[0102] Referring to FIG. 5, the data frame may include three data
streams 591, 592, and 593 in order to support two terminals, for
example, a first terminal and a second terminal The data streams
591 and 592 may be transmitted to the first terminal, and the data
stream 593 may be transmitted to the second terminal.
[0103] A second channel estimation field 540 included in each of
the data streams 591, 592, and 593 may include channel estimation
signal groups 541, 542, and 543 in the same time interval. When the
data streams 591, 592, and 593 are independently separated and
transmitted, each of the first terminal and the second terminal may
estimate a channel between a base station and each of the first
terminal and the second terminal based on the simultaneously
transmitted channel estimation signal groups 541, 542, and 543.
[0104] A signal detection field 511, a first channel estimation
field 512, a common control field 513, a power amplifier training
field 530, an individual control field 550, and a data field 560 of
FIG. 5 are configured to be similar to the description made above
for similar items with reference to FIGS. 2 through 4.
[0105] In FIG. 5 two terminals receiving data frames were
described. According to another embodiment, a single terminal or at
least three terminals may receive data frames. In one example, the
channel estimation signal groups 541, 542, and 543 included in the
second channel estimation field 540 may be included in the same
time interval.
[0106] FIG. 6 illustrates an example of data streams including
channel estimation signal groups in different time intervals with
respect to the same terminal according to an embodiment.
[0107] Referring to FIG. 6, data streams 691 and 692 are
transmitted to a first terminal, and data streams 693, 694, and 695
are transmitted to a second terminal.
[0108] Each of the data streams 691, 692, 693, 694, and 695
includes a second channel estimation field 640 to accurately
estimate a channel between a transmission apparatus and each of the
first terminal and the second terminal. The second channel
estimation field 640 may include channel estimation signal groups
641, 642, 643, 644, and 645.
[0109] The data streams 691 and 692 include the channel estimation
signal groups 641 and 642 in different time intervals,
respectively. In the different data streams 691 and 692 transmitted
to the first terminal, a time interval of the channel estimation
signal group 641 does not overlap a time interval of the channel
estimation group 642.
[0110] Similarly, in the different data streams 693, 694, and 695
transmitted to the second terminal, time intervals of the channel
estimation signal groups 643, 644, and 645 do not overlap each
other.
[0111] The first terminal may estimate a channel between a transmit
antenna and a receive antenna using the channel estimation signal
groups 641 and 642. The second terminal may also estimate a channel
between a transmit antenna and a receive antenna using the channel
estimation signal groups 643, 644, and 645.
[0112] A signal detection field 611, a first channel estimation
field 612, a common control field 613, a power amplifier training
field 630, an individual control field 650, and a data field 660 of
FIG. 6 are configured to be similar to the description made above
for similar items with reference to FIGS. 2 through 5.
[0113] In FIG. 6 two terminals receiving data frames were
described. According to another embodiment, a single terminal or at
least three terminals may receive data frames. In one example,
channel estimation signal groups included in different data streams
received by the same terminal may be included in different time
intervals, respectively.
[0114] FIG. 7 illustrates an example of data streams including
channel estimation signal groups in different time intervals with
respect to different terminals according to an embodiment.
[0115] Referring to FIG. 7, data streams 791 and 792 are
transmitted to a first terminal, and data streams 793 and 794 are
transmitted to a second terminal.
[0116] Data streams transmitted to different terminals may include
channel estimation signal groups in different time intervals. For
example, a first set of channel estimation signal groups 741, 742,
743, and 744 that are included in the data streams 791 and 792
transmitted to the first terminal, and a second set of channel
estimation signal groups 745, 746, 747, and 748 that are included
in the data streams 793 and 794 transmitted to the second terminal
may be included in different time intervals. Accordingly, it is
possible to completely remove an interference effect and accurately
estimate a channel with respect to different terminals.
[0117] Precoded data transmitted to the same terminal may include
channel estimation signal groups in the same time interval. In FIG.
7, the first terminal may estimate a channel between a transmit
antenna and a receive antenna by combining the first set of channel
estimation signal groups 741, 742, 743, and 744. The second
terminal may estimate a channel between a transmit antenna and a
receive antenna by combining the second set of channel estimation
signal groups 745, 746, 747, and 748.
[0118] A signal detection field 711, a first channel estimation
field 712, a common control field 713, a power amplifier training
field 730, an individual control field 750, and a data field 760 of
FIG. 7 are configured to be similar to the description made above
for similar items with reference to FIG. 2.
[0119] In FIG. 7 two terminals receiving data frames were
described. According to another embodiment, a single terminal or at
least three terminals may receive data frames. In one example, data
streams transmitted to different terminals may include channel
estimation signal groups in different time intervals.
[0120] FIG. 8 illustrates an example of a data frame in which data
stream are independently separated and transmitted using
precoding.
[0121] Referring to FIG. 8, data streams 891 and 892 may be
transmitted to a first terminal, and data streams 893 and 894 may
be transmitted to a second terminal.
[0122] Each of the data streams 891, 892, 893, and 894 may include
a second channel estimation field 840 to estimate a channel between
a transmission apparatus and each of the first terminal and the
second terminal. The second channel estimation field 840 may
include channel estimation signal groups 841, 842, 843, 844, 851,
852, 853, 854, 855, 856, 857, and 858.
[0123] The channel estimation signal groups 841, 842, 843, and 844
included in the data streams 891 and 892 transmitted to the first
terminal, and the channel estimation signal groups 851, 852, 853,
854, 855, 856, 857, and 858 included in the data streams 893 and
894 transmitted to the second terminal may temporally overlap.
[0124] The first terminal may apply an orthogonality to the channel
estimation signal groups 841, 842, 843, and 844 by multiplying a
unitary matrix and each of the channel estimation signal groups
841, 842, 843, and 844. The second terminal may apply the
orthogonality to the channel estimation signal groups 851, 852,
853, 854, 855, 856, 857, and 858 by multiplying a unitary matrix
and each of the channel estimation signal groups 851, 852, 853,
854, 855, 856, 857, and 858. Undesirable signals can then be
discarded due to the applied orthogonality. Each of the first
terminal and the second terminal may estimate a channel between a
transmission apparatus and each of the first terminal and the
second terminal using the channel estimation signal groups 841,
842, 843, 844, 851, 852, 853, 854, 855, 856, 857, and 858 with the
assigned orthogonality.
[0125] A signal detection field 811, a first channel estimation
field 812, a common control field 813, a power amplifier training
field 830, an individual control field 860, and a data field 870 of
FIG. 7 are configured to be similar to the description made above
for similar items with reference to FIG. 2.
[0126] In FIG. 8 two terminals receiving data frames were
described. According to another embodiment, a single terminal or at
least three terminals may receive data frames. In one example,
channel estimation signal groups included in data streams may
temporally overlap. Each of the terminals may estimate a channel
using a unitary matrix.
[0127] FIG. 9 illustrates a configuration of a transmission
apparatus 900 according to an embodiment.
[0128] The transmission apparatus 900 may include a detection
signal generator 911, a first channel estimation signal generator
912, a common control information generator 913, a power amplifier
training signal generator 920, an individual control information
generator 930, a second channel estimation signal generator 940, a
controller 950, a precoder 960, and a transmitter 970.
[0129] The detection signal generator 911 may generate a detection
signal. Each of terminals 980 and 990 may detect a data frame
transmitted from the transmission apparatus 900, using the
detection signal included in the data frame. Each of the terminals
980 and 990 may perform a time synchronization with respect to a
current data frame. In addition, each of the terminals 980 and 990
may estimate a coarse frequency offset using the detection
signal.
[0130] The first channel estimation signal generator 912 may
generate a first channel estimation signal. Each of the terminals
980 and 990 may estimate a fine frequency offset based on the first
channel estimation signal. In addition, each of the terminals 980
and 990 may receive non-precoded common control information.
[0131] The detection signal and the first channel estimation signal
are not precoded and are transmitted to each of the terminals 980
and 990.
[0132] The common control information generator 913 may generate
common control information with respect to the terminals 980 and
990. Each of the terminals 980 and 990 may include at least one
receive antenna. For example, the terminal 980 may include receive
antennas 981 and 982, and the terminal 990 may include a receive
antenna 991.
[0133] The "common control information" denotes control information
transmitted to all the terminals 980 and 990 included within a
coverage of the transmission apparatus 900. The common control
information is transmitted without being precoded. The common
control information may include information associated with common
controls of the data frame. The common control information may
include a precoding method applied to the data frame, a number of
terminals supported by the data frame, and channel estimation
signal groups. The common control information is not precoded with
respect to a particular terminal and transmitted to all terminals
receiving the data frame.
[0134] As described before, a number of data frames included in the
data frame, a duration or a length of the second channel estimation
field and a format of the second channel estimation field may
instead be included in the individual control information to be
describe below.
[0135] The power amplifier training signal generator 920 may
generate a power amplifier training signal. Each of the terminals
980 and 990 may perform a multi-antenna AGC using the power
amplifier training signal. The precoder 960 may generate the
precoded data by additionally precoding the power amplifier
training signal.
[0136] The individual control information generator 930 may
generate individual control information with respect to each of the
terminals 980 and 990. The "individual control information" denotes
control information individually determined for each of the
terminals 980 and 990. The individual control information may
include one or more of: a data field or a data frame transmitted to
a corresponding terminal, a modulation and coding method applied to
the data field, a bandwidth of a using channel, a channel
smoothing, a channel aggregation, an error correction code, a guard
interval, and a precoding method applied to the data frame.
[0137] As described before, a length of the data field or the data
frame transmitted to a corresponding terminal, a modulation and
coding method applied to the data field, a channel bandwidth, a
channel smoothing, a channel aggregation, an error correction code
and a length of a guard interval may instead be included in the
common control information.
[0138] The second channel estimation signal generator 940 may
generate a second channel estimation signal used to estimate a
channel for each of multi-accessing terminals 980 and 990. The
second channel estimation signal may include at least one channel
estimation signal group.
[0139] The terminals 980 and 990 may receive a different number of
data streams. Each of the data streams may include a channel
estimation signal. A number of channel estimation signal groups
included in each channel estimation signal may be determined based
on a number of data streams received by each of the terminals 980
and 990.
[0140] The controller 950 may individually determine a number of
data streams transmitted to each of the terminals 980 and 990. The
controller 950 may determine a number of training signal groups
included in each of the data streams based on the number of data
streams. The data frame may include a plurality of data streams.
The channel estimation signal may include a plurality of channel
estimation signal groups. The transmitter 970 may transmit a
plurality of precoded data to a particular terminal included in the
plurality of terminals, e.g., either of the terminals 980 and 990.
Each of channel estimation signals included in the plurality of
precoded data may be included in a different time interval.
[0141] The terminal 980 may receive a plurality of data streams.
The data streams received by the terminal 980 may include training
signal groups in different time intervals, respectively. When the
training signal groups do not overlap each other, the terminal 980
may effectively estimate a channel.
[0142] An example in which each of the terminals 980 and 990
estimates a channel between the transmission apparatus 900 and each
of the terminals 980 and 990 using the channel estimation signal
group is described above for similar items with reference to FIGS.
4 through 8.
[0143] The precoder 960 may generate precoded data with respect to
each of the terminals 980 and 990 by precoding the individual
control information and data with respect to each of the terminals
980 and 990. The precoded data may be transmitted to each of the
terminals 980 and 990. However, each of the terminals 980 and 990
may decode only precoded data that is precoded with respect to a
corresponding terminal.
[0144] The precoder 960 may generate the precoded data by
additionally precoding the power amplifier training signal and the
second channel estimation signal.
[0145] The transmitter 970 may transmit, to the terminals 980 and
990, a data frame including a plurality of data streams. The
transmitter 970 may transmit, to the terminals 980 and 990, a data
frame including the common control information and the precoded
data according to a multi-user multiple input multiple output
(MU-MIMO) communication method. The transmitter 970 may transmit
the data frame to each of the terminals 980 and 990 using a
plurality of transmit antennas 971, 972, and 973. Each data stream
may include a detection signal, a first channel estimation signal,
and common control information that are not precoded, and precoded
data that is precoded with respect to each of the terminals 980 and
990.
[0146] Each of the terminals 980 and 990 may decode the
non-precoded common control information and may also decode the
precoded data precoded with respect to a corresponding
terminal.
[0147] Data included in the precoded data may be modulated by
selecting a single modulation method from various modulation
methods based on a channel status. For example, the individual
control information may be modulated using a predetermined
modulation method. The data may also be error correction coded by
selecting a single error correction code method from various error
correction code methods. For example, the individual control
information may be error correction coded using a predetermined
error correction code method. The modulation method and the error
correction code method applied to the data may be included in the
individual control information.
[0148] The individual control information may be modulated using a
modulation method predetermined between the transmission apparatus
900 and each of the terminals 980 and 990, or may be error
correction coded using an error correction code method
predetermined between the transmission apparatus 900 and each of
the terminals 980 and 990. For example, the terminals 980 and 990
may simply decode the individual control information without
reference to other control information, and may decode data using
the decoded individual control information.
[0149] The modulation method or the error correction code method
applied to the individual control information may be included in
the common control information.
[0150] FIG. 10 illustrates a configuration of a terminal according
to an embodiment.
[0151] The terminal 1000 may include a receiver 1060, a signal
detector 1011, a first channel estimator 1012, a common control
information decoder 1013, a power amplifier controller 1020, a
second channel estimator 1030, a data decoder 1040, and an
individual control information decoder 1050.
[0152] The receiver 1060 may receive a data frame from a
transmission apparatus 1070. The data frame may include a data
stream or a plurality of data streams. The data stream may include
a signal detection field, a first channel estimation field, a
common control field, and precoded data. The transmission apparatus
1070 may transmit the precoded data using a plurality of transmit
antennas 1071, 1072, and 1073.
[0153] The signal detector 1011 may detect a signal transmitted
from the transmission apparatus 1070. The signal may be detected
using a detection signal included in the signal detection field.
The signal detector 1011 may perform a coarse AGC using the
detection signal, and may also estimate a coarse frequency offset.
The signal detector 1011 may perform a time synchronization with
respect to a current data frame using the detection signal.
[0154] The first channel estimator 1012 may estimate a fine
frequency offset using a first channel estimation signal included
in the first channel estimation field. The first channel estimator
1012 may estimate a channel between the transmission apparatus 1070
and the terminal 1000 in order to decode common control
information.
[0155] The common control information decoder 1013 may decode the
common control information from the data frame.
[0156] The "common control information" denotes control information
decodable by the terminal 1000 and by a terminal 1080 included
within a coverage of the transmission apparatus 1070. The common
control information may include the data frame transmitted to the
terminals 1000 and 1080. The common control information may include
one or more of: a precoding method applied to the data frame, a
number of terminals supported by the data frame, a number of data
streams included in the data frame, and an interval or a length of
a second channel estimation field, and a format of the second
channel estimation field. As described before, a number of data
frames included in the data frame, a duration or a length of the
second channel estimation field and a format of the second channel
estimation field may instead be included in the individual control
information. The common control information is transmitted without
being precoded with respect to a particular terminal.
[0157] The power amplifier controller 1020 may accurately control a
gain of a power amplifier using the power amplifier training signal
included in the power amplifier training field.
[0158] The second channel estimator 1030 may estimate a channel
between the transmission apparatus 1070 and the terminal 1000 using
the second channel estimation signal included in the second channel
estimation field. The second channel estimation signal may include
at least one channel estimation signal group.
[0159] The terminal 1000 may receive a plurality of data streams.
According to an example embodiment, a number of channel estimation
signal groups included in each of the data streams received by the
terminal 1000 may be determined based on a number of the data
streams received by the terminal 1000.
[0160] According to another example embodiment, channel estimation
signals included in the data streams received by the first terminal
1000 may be included in different time intervals.
[0161] An example in which the terminal 1000 estimates a channel
between the terminal 1000 and the transmission apparatus 1070 using
the channel estimation signal group is described above for similar
items with reference to FIGS. 4 through 8.
[0162] The individual control information decoder 1050 may decode
the individual control information based on the common control
information and a channel estimation result of the second channel
estimator 1030. The "individual control information" denotes
control information individually determined with respect to each of
the terminals 1000 and 1080. The individual control information may
include one or more of: a length of a data field or a data frame
transmitted to a corresponding terminal, a modulation and coding
method applied to the data field, a channel bandwidth, a channel
smoothing, a channel aggregation, an error correction code, a
length of a guard interval, and a precoding method applied to the
data frame. As described before, a length of the data field or the
data frame transmitted to a corresponding terminal, a modulation
and coding method applied to the data field, a channel bandwidth, a
channel smoothing, a channel aggregation, an error correction code
and a length of a guard interval may instead be included in the
common control information.
[0163] The data decoder 1040 may decode data included in a data
stream, based on the individual control information and a channel
estimation result of the second channel estimator 1030. A
modulation method selected from various modulation methods or an
error correction code method selected from various error correction
code methods may be applicable to the data transmitted to each of
the terminals 1000 and 1080, based on a channel status.
[0164] A modulation method or an error correction code method
predetermined between the terminal 100 and the transmission
apparatus 1070 may be applicable to the individual control
information. In one example, the terminal 1000 may simply decode
the individual control information without reference to other
control information, and may decode data using the decoded
individual control information.
[0165] The transmission apparatus 1070 may precode and transmit
individual control information and data determined with respect to
each of the terminals 1000 and 1080.
[0166] FIG. 11 illustrates a method of receiving data according to
an embodiment.
[0167] In operation 1110, a terminal may receive a data frame from
a transmission apparatus. The terminal may detect the data frame
using a detection signal included in the data frame. The terminal
may perform a coarse AGC using the detection signal. The terminal
may perform a time synchronization with respect to the current data
frame using the detection signal.
[0168] In operation 1120, the terminal may perform a first channel
estimation using a first channel estimation signal included in the
data frame. The "first channel estimation" denotes an operation of
estimating a channel between the transmission apparatus and the
terminal in order to decode a non-precoded field included in the
data frame. Also, in operation 1120, the terminal may estimate a
fine frequency offset using the first channel estimation
signal.
[0169] In operation 1130, the terminal may decode common control
information included in the data frame. The terminal may decode
precoded data included in the data frame, based on the common
control information.
[0170] In operation 1140, the terminal may perform a fine AGC using
a power amplifier training signal included in the data frame.
[0171] In operation 1150, the terminal may perform a second channel
estimation using the second channel estimation field included in
the data frame. The "second channel estimation" denotes an
operation of estimating a channel between the transmission
apparatus and the terminal in order to decode precoded data.
[0172] In operation 1160, the terminal may decode the individual
control information included in the data frame.
[0173] In operation 1170, the terminal may decode data included in
the data frame, based on a second channel estimation result and the
individual control information.
[0174] FIG. 12 illustrates a method of transmitting data according
to an embodiment.
[0175] In operation 1210, a transmission apparatus may generate a
detection signal. A terminal may detect a data frame transmitted
from the transmission apparatus, using the detection signal
included in the data frame, and may perform a coarse frequency
offset. The terminal may perform a time synchronization with
respect to the current data frame using the detection signal.
[0176] In operation 1220, the transmission apparatus may generate a
first channel estimation signal. The terminal may estimate a
channel between the transmission apparatus and the terminal based
on the first channel estimation signal, and may decode non-precoded
information or non-precoded signals using the above estimation
result.
[0177] In operation 1230, the transmission apparatus may generate
common control information. The common control information may
include control information associated with the data frame
transmitted from the transmission apparatus.
[0178] In operation 1240, the transmission apparatus may generate a
power amplifier training signal. The terminal may perform a fine
AGC using the power amplifier training signal.
[0179] In operation 1250, the transmission apparatus may generate
individual control information. The "individual control
information" denotes control information individually determined
with respect to each terminal.
[0180] In operation 1260, the transmission apparatus may generate a
second channel estimation signal. The terminal may estimate a
channel between the transmission apparatus and the terminal using
the second channel estimation signal, and may decode a precoded
signal or precoded information using the above estimation
result.
[0181] The second channel estimation signal may include a plurality
of training signal groups. A number of channel estimation signal
groups included in the second channel estimation signal may be
determined based on a number of data streams received by the
terminal
[0182] The channel estimation signal groups included in the second
channel estimation signal may be included in different time
intervals.
[0183] In operation 1270, the transmission apparatus may generate
precoded data by precoding the data individual control information
and data with respect to each terminal. The transmission apparatus
may generate the precoded data by additionally precoding the power
amplifier training signal and the second channel estimation
signal.
[0184] In operation 1280, the transmission apparatus may transmit,
to a plurality of terminals, common control information and the
precoded data. The data frame may include the detection signal and
the first channel estimation signal. The transmission apparatus may
transmit the data frame using a MU-MIMO communication method. In
one example, the common control information may include information
associated with a number of terminals supported by the MU-MIMO
communication method.
[0185] The processes, functions, methods and/or software described
above may be recorded, stored, or fixed in one or more
computer-readable storage media that includes program instructions
to be implemented by a computer to cause a processor to execute or
perform the program instructions. The media may also include, alone
or in combination with the program instructions, data files, data
structures, and the like. The media and program instructions may be
those specially designed and constructed, or they may be of the
kind well-known and available to those having skill in the computer
software arts. Examples of computer-readable media include magnetic
media, such as hard disks, floppy disks, and magnetic tape; optical
media such as CD-ROM disks and DVDs; magneto-optical media, such as
optical disks; and hardware devices that are specially configured
to store and perform program instructions, such as read-only memory
(ROM), random access memory (RAM), flash memory, and the like.
Examples of program instructions include machine code, such as
produced by a compiler, and files including higher level code that
may be executed by the computer using an interpreter. The described
hardware devices may be configured to act as one or more software
modules in order to perform the operations and methods described
above, or vice versa. In addition, a computer-readable storage
medium may be distributed among computer systems connected through
a network and computer-readable codes or program instructions may
be stored and executed in a decentralized manner.
[0186] As a non-exhaustive illustration only, the terminal device
described herein may refer to mobile devices such as a cellular
phone, a personal digital assistant (PDA), a digital camera, a
portable game console, and an MP3 player, a portable/personal
multimedia player (PMP), a handheld e-book, a portable laptop PC, a
global positioning system (GPS) navigation, and devices such as a
desktop PC, a high definition television (HDTV), an optical disc
player, a setup and/or set-top box, and the like capable of
wireless communication or network communication consistent with
that disclosed herein.
[0187] A computing system or a computer may include a
microprocessor that is electrically connected with a bus, a user
interface, and a memory controller. It may further include a flash
memory device. The flash memory device may store N-bit data via the
memory controller. The N-bit data is processed or will be processed
by the microprocessor and N may be 1 or an integer greater than 1.
Where the computing system or computer is a mobile apparatus, a
battery may be additionally provided to supply operation voltage of
the computing system or computer.
[0188] It will be apparent to those of ordinary skill in the art
that the computing system or computer may further include an
application chipset, a camera image processor (CIS), a mobile
Dynamic Random Access Memory (DRAM), and the like. The memory
controller and the flash memory device may constitute a solid state
drive/disk (SSD) that uses a non-volatile memory to store data.
[0189] A number of example embodiments have been described above.
Nevertheless, it will be understood that various modifications may
be made. For example, suitable results may be achieved if the
described techniques are performed in a different order and/or if
components in a described system, architecture, device, or circuit
are combined in a different manner and/or replaced or supplemented
by other components or their equivalents. Accordingly, other
implementations are within the scope of the following claims.
* * * * *